The present invention relates to a novel cyanine compound which can be used as, for example, a coloring material, a sensitization dye for photographic use, a recording dye for use in optical information recording media, a staining agent of biological samples such as cells, a pharmaceutical agent and the like. The present invention also relates to an optical filter that uses the cyanine compound as a coloring material, and to an optical information recording medium such as an optical disc that uses the novel cyanine compound.
Cyanine dyes having a hetero ring as the terminal group in which a naphthoquinone nucleus and an imidazole nucleus are fused are disclosed for example in Chemical Abstracts, vol. 71, 22892K, Chemical Abstracts, vol. 62, p. 11942, and Chemical Abstracts, vol. 58, p. 6818. These prior art dyes, however, are not versatile, because the structures of the substituent groups or conjugated methine chains are limited.